During surgery for inserting implants, it may be necessary to monitor the position of the inserted implant as well as to monitor a sub implant to be inserted and to be positioned with respect to the implant. A current method of inserting implant is typically accomplished by positioning the implant on the corresponding anatomical location and inserting a respective sub implant with the assistance of fluoroscopy. This, however, is an iterative process, which requires a repeated positioning of the sub implant with respect to the implant and taking a plurality of fluoroscopic images of the situation to monitor whether and in which direction the sub implant has to be repositioned with respect to the implant. For overcoming this iterative process problem, there are several proposals for providing a three-dimensional image of the situation in order to have a three-dimensional information allowing to conduct a positioning without repeated monitoring shots of a fluoroscopic imaging system. For this purpose, US 2010/0030219 A1 and US 2005/0027304 A1 describe an imaging, wherein the three-dimensional information is obtained by taking two different two-dimensional images from different viewing positions, i.e. angles, so as to generate a three-dimensional information. However, this requires taking two two-dimensional images, which, when using a standard C-arm fluoroscopic imaging system, requires a repositioning of the imaging system to obtain an image from a differing viewing position. This, however, may lead to a displacement of the imaged situation during repositioning, so that the resulting three-dimensional information may be erroneous.